1. Technical Field
The present invention relates generally to anti-CD40 antibodies, compositions and methods of using same. Such antibodies are useful, for example, in methods for treating a variety of oncological diseases.
2. Description of the Related Art
The majority of leukemias and lymphomas originate from malignant transformation of B-lineage cells. The expression of cell surface B-lineage-restricted antigens such as CD20 makes it an attractive target for antibody therapy. Antibody therapeutics have dramatically changed the management of patients with non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL). Since the approval of rituximab, the antibody alone or in combination with chemotherapy has remarkably improved response rates, long-term outcomes, and quality of life (Chinn P, Braslawsky G, White C, et al. Antibody therapy of non-Hodgkin's B-cell lymphoma. Cancer Immunol Immunother 2003; 52:257-280; Rastetter W, Molina A, White C A. Rituximab: Expanding role in therapy for lymphomas and autoimmune diseases. Annu Rev Med 2004; 55:477-503). However, a substantial number of patients exhibit either primary or acquired resistance to rituximab, suggesting that current approaches targeting CD20 have limitations in clinical outcomes, and there is a need for improvement by developing novel immunotherapeutics for B cell lymphoma and leukemia with distinct mechanisms of action (Stolz C, Schuler M. Molecular mechanisms of resistance to Rituximab and pharmacologic strategies for its circumvention. Leukemia and lymphoma. 2009; 50(6):873-885; Bello C, Sotomayor E M. Monoclonal antibodies for B-cell lymphomas: Rituximab and beyond. Hematology Am Soc Hematol Educ Program 2007; 233-242; Dupire S, Coiffier B. Targeted treatment and new agents in diffuse large B cell lymphoma. Int J Hematol 2010; June 18 (online)), such as the anti-CD40 mAb, APX005.
The Role of CD40 in the Regulation of Immune Responses
Full activation of T cells requires two distinct but synergistic signals. The first signal, delivered through the T-cell antigen receptor, is provided by antigen and MHC complex on APCs and is responsible for the specificity of the immune response. The secondary, or costimulatory, signal is through the interaction of CD28 with B7-1 (CD80)/B7-2 (CD86), and CD40 with CD40L, which are required to mount a full scale T cell response. In the absence of costimulatory signals, T cells may undergo unresponsiveness (anergy) or programmed cell death (apoptosis) upon antigen stimulation.
CD40, a member of the TNF receptor (TNFR) superfamily, is expressed primarily on B cells and other antigen-presenting cells (APCs) such as dendritic cells and macrophages. CD40 ligand (CD40L) is expressed primarily by activated T cells.
CD40 and CD40L interaction serves as a costimulatory signal for T cell activation. CD40-CD40L engagement on resting B cells induces proliferation, immunoglobulin class switching, antibody secretion, and also has a role in the development of germinal centers and the survival of memory B cells, all of which are essential to humoral immune responses (Kehry M R. J Immunol 1996; 156: 2345-2348). Binding of CD40L to CD40 on dendritic cells induces DC maturation as manifested by increasing expression of co-stimulatory molecules such as B7 family (CD80, CD86) and production of proinflammatory cytokines such as interleukin 12. These lead to potent T cell responses (Stout, R. D., J. Suttles. 1996. Immunol. Today 17:487-492; Brendan O'Sullivan, Ranjeny Thomas. Critical Reviews in Immunology 2003; 23: 83-107; Cella, M., D. Scheidegger, K. Palmer-Lehmann, P. Lane, A. Lanzavecchia, G. Alber. J. Exp. Med. 1996; 184:747-452).
CD40 signal transduction activates multiple pathways including NF-KappaB (Nuclear Factor-KappaB), MAPK (Mitogen-Activated Protein Kinase) and STAT3 (Signal Transducers and Activators of Transcription-3) (Pype S, et al. J Biol Chem. 2000 Jun. 16; 275(24):18586-93) that regulate gene expression through activation of Activating Proteins, c-Jun, ATF2 (Activating Transcription Factor-2) and Rel transcription factors (Dadgostar H, et al. Proc Natl Acad Sci USA. 2002 Feb. 5; 99(3):1497-502). The TNFR-receptor associated factor adaptor proteins (e.g., TRAF1, TRAF2, TRAF3, TRAF5, and TRAF6) interact with this receptor and serve as mediators of the signal transduction. Depending on the particular cell type, CD40 engagement results in a particular gene expression pattern. Genes activated in response to CD40 signaling include numerous cytokines and chemokines (IL-1, IL-6, IL-8, IL-10, IL-12, TNF-Alpha, and Macrophage Inflammatory Protein-1Alpha (MIP1Alpha). In certain cell types, activation of CD40 may result in production of cytotoxic radicals (Dadgostar et al., Supra), COX2 (Cyclooxygenase-2), and production of NO (Nitric Oxide).
The Role of CD40 in Tumors
CD40 is not only expressed by normal immune cells but also by many malignant cells. In particular, CD40 is over-expressed in B-lineage NHLs, chronic lymphocytic leukemias (CLLs), hairy cell leukemias (HCLs), Hodgkin's disease (Uckun F M, Gajl-Peczalska K, Myers D E, et al. Blood 1990; 76:2449-2456; O'Grady J T, Stewart S, Lowrey J, et al. Am J Pathol 1994; 144: 21-26), multiple myeloma (Pellat-Deceunynck C, Bataille R, Robillard N, Harousseau J L, Rapp M J, Juge-Morineau N, Wijdenes J, Amiot M. Blood. 1994; 84(8):2597-603), as well as in carcinomas of the bladder, kidney, ovary, cervix, breast, lung, nasopharynx, and malignant melanoma (Young L S, Eliopoulos A G, Gallagher N J, et al. Immunol Today 1998; 19:502-6; Ziebold J L, Hixon J, Boyd A, et al. Arch Immunol Ther Exp (Warsz) 2000; 48: 225-33; Gladue R, Cole S, Donovan C, et al. J Clin Oncol 2006; 24 (18S):103s).
Ligation of CD40 on the surface of tumor cells, which in many cases, mediates a direct cytotoxic effect, results in tumor regression through apoptosis and necrosis (Grewal I S, Flavell R A. Annu Rev Immunol 1998; 16:111-35; van Kooten C, Banchereau J. J Leukoc Biol 2000; 67(1):2-17). Although the exact functions of CD40 in tumor cells are unclear (Tong A W, Stone M J. Cancer Gene Ther. 2003 10(1):1-13), engagement of CD40 in vitro inhibits the growth of solid tumor cells and high-grade B cell lymphoma cells (Magi Khalil and Robert H. Vonderheide. Update Cancer Ther 2007; 2(2): 61-65; Young L S, Eliopoulos A G, Gallagher N J, Dawson C W. Immunol Today 1998; 19(11):502-6; Funakoshi S, Longo D L, Beckwith M, et al. Blood 1994; 83(10):2787-94; Hess S, Engelmann H. J Exp Med 1996; 183(1):159-67; Eliopoulos A G, Dawson C W, Mosialos G, et al. Oncogene 1996; 13(10):2243-54; von Leoprechting A, van der Bruggen P, Pahl H L, Aruffo A, Simon J C. Cancer Res 1999; 59(6):1287-94). These effects contrast with proliferation induced after engagement of CD40 on non-neoplastic B cells and dendritic cells.
In addition to direct tumor inhibition, activation of CD40 signaling rescues the function of antigen-presenting cells in tumor-bearing hosts and triggers or restores active immune responses against tumor-associated antigens. CD40 agonists have been reported to overcome T-cell tolerance in tumor-bearing mice, evoke effective cytotoxic T-cell responses against tumor-associated antigens, and enhance the efficacy of antitumor vaccines (Eliopoulos A G, Davies C, Knox P G, et al. Mol Cell Biol 2000; 20(15): 5503-15; Tong A W, Papayoti M H, Netto G, et al. Clin Cancer Res 2001; 7(3):691-703).
CD40 as Molecular Target
CD40 is overexpressed on a wide range of malignant cells. The roles of CD40 in tumor inhibition and stimulation of the immune system make CD40 an attractive target for an antibody-based immunotherapy (van Mierlo G J, den Boer A T, Medema J P, et al. Proc Natl Acad Sci USA. 2002; 99(8): 5561-5566; French R R, Chan H T, Tutt A L, Glennie M J. Nat Med. 1999; 5(5):548-553). Anti-CD40 antibodies may act against cancer cells via multiple mechanisms: (i) antibody effector function such as ADCC, (ii) a direct cytotoxic effect on the tumor cells, and (iii) activation of anti-tumor immune responses.
Anti-CD40 Therapeutic Antibodies in Development
Several anti-CD40 antibodies have been reported to have potential as anti-tumor therapeutics. CP-870,893 is a fully human IgG2 CD40 agonist antibody developed by Pfizer. It binds CD40 with a KD of 3.48×10−10 M, but does not block binding of CD40L (see e.g., U.S. Pat. No. 7,338,660). CP-870893 has shown ADCC effects; possibly due to its IgG2 isotype. Thus, this antibody acts as a CD40 agonist (i.e., does not affect CD40L binding), induces proapoptotic signaling, and activates DCs and immune surveillance. However, this antibody does not mediate ADCC.
HCD122 is a fully human IgG1 CD40 antagonist antibody developed by Novartis. It binds to CD40 with a KD of 5.1×10−10 M, blocks CD40 binding to CD40L, inhibits CD40-ligand induced signaling and biological effects on B cells and certain primary CLL and MM cells (Tai Y T, et al. Cancer Res. 2005 Jul. 1; 65(13):5898-906; Luqman M, Klabunde S, et al: Blood 112:711-720, 2008). The major mechanism of action for its anti-tumor effect in vivo is ADCC (Long L, et al. 2005 IMF Oral Presentation and Abstract No. 3; Blood 2004, 104(11, Part 1): Abst 3281). Due to its antagonist feature, this antibody may not directly induce CD40-mediated anti-tumor immune response.
SGN-40 is a humanized IgG1 antibody developed by Seattle Genetics from mouse antibody clone S2C6, which was generated using a human bladder carcinoma cell line as the immunogen. It binds to CD40 with a KD of 1.0×10−9 M and works through enhancing the interaction between CD40 and CD40L, thus exhibiting a partial agonist effect (Francisco J A, et al., Cancer Res, 60: 3225-31, 2000). SGN-40 delivers proliferation inhibitory and apoptosis signals to a panel of B lymphoma lines originated from high-grade non-Hodgkin's lymphoma and MM cells (Tai Y T, Catley L P, Mitsiades C S, et al. Cancer Res 2004; 64(8):2846-2852). In vitro and in vivo studies suggest that both apoptotic signaling and antibody effector function via ADCC contribute to antitumor activity of SGN-40 (Law C L, Gordon K A, Collier J, et al: Cancer Res 2005; 65:8331-8338). A Recent study suggested that the anti-tumour activity of SGN-40 significantly depends on Fc interactions with the effector cells and that macrophages are the major effectors contributing to its therapeutic activities (Oflazoglu E, et al. Br J Cancer. 2009 Jan. 13; 100(1):113-7. Epub 2008 Dec. 9). Since SGN-40 is a partial agonist and requires CD40L expressed on T cells, SGN-40 may have limited ability to fully boost the anti-tumor immune response.
Accordingly, there remains a need in the art for novel immunotherapeutics that target CD40 and that act as agonist for this target, activate dendritic cells and immune surveillance and which activate ADCC, thereby providing improved anti-cancer properties.